Estimating absorption coefficients of colored dissolved organic matter (CDOM) using a semi-analytical algorithm for southern Beaufort Sea waters: application to deriving concentrations of dissolved organic carbon from space

[摘要] A series of papers have suggested that freshwater discharge, including alarge amount of dissolved organic matter (DOM), has increased since themiddle of the 20th century. In this study, a semi-analytical algorithm forestimating light absorption coefficients of the colored fraction of DOM(CDOM) was developed for southern Beaufort Sea waters using remote sensingreflectance at six wavelengths in the visible spectral domain correspondingto MODIS ocean color sensor. This algorithm allows the separation of coloreddetrital matter (CDM) into CDOM and non-algal particles (NAP) through thedetermination of NAP absorption using an empirical relationship between NAPabsorption and particle backscattering coefficients. Evaluation usingindependent datasets, which were not used for developing the algorithm, showedthat CDOM absorption can be estimated accurately to within an uncertainty of35% and 50% for oceanic and coastal waters, respectively. Aprevious paper (Matsuoka et al., 2012) showed that dissolved organic carbon(DOC) concentrations were tightly correlated with CDOM absorption in ourstudy area (r² = 0.97). By combining the CDOM absorption algorithmtogether with the DOC versus CDOM relationship, it is now possible toestimate DOC concentrations in the near-surface layer of the southernBeaufort Sea using satellite ocean color data. DOC concentrations in thesurface waters were estimated using MODIS ocean color data, and the estimatesshowed reasonable values compared to in situ measurements. We propose aroutine and near real-time method for deriving DOC concentrations from space,which may open the way to an estimate of DOC budgets for Arctic coastalwaters.

[学科分类] 地球化学与岩石